Solution Tension and Toxicity in Lipolysis. 283 
In the case of zinc the reagent and the control acidity are equal at 
the point of totalinhibition. This same relation of control and re- 
agent acidity is again seen with greater concentration of the enzyme 
for cadmium in Table XVI, cobalt in Table XV, and zinc in Table 
XVII. This indicates a difference in the action between zinc and 
the other two, anda similarity between cobalt and cadmium, Refer- 
ring to Tables XIII, XX, and XXI, we see that copper, lead, and zinc 
are alike, in that the acidity of control is less than the sum of reagent 
acidity and the initial acidity of the enzyme solution, but that the 
control acidity is greater than that of the reagent, and that the differ- 
ence decreases to zero at the point of total inhibition. That this 
relation holds in the case of zinc, at least in the absence of butyrate, 
is seen in Table XIII. In Table XIX mercury seems to be different 
in behavior from any of the others. At the point of total inhibition 
the acidity of the control is less than that of the reagent. Mercury 
is the only one which precipitates the enzyme during incubation in 
the 0.0125 per cent concentration of the enzyme. These relations 
acquire significance when we find that the similarities are correlated 
with relative toxicity, at least in the case of the highest dilution of 
the enzyme tried. Thus copper, lead, and zinc are equal, which is 
also true of cobalt and cadmium, The more acidity consumed in the 
union of the reagent and the enzyme substance, the greater the — 
toxicity. ; 
It is the intention to further investigate some of the correlations 
apparent in this study, but so far as ionic potential as a determining 
factor in. toxicity is concerned, my results, in accord with those of 
Berg and Gies,' not only fail to furnish support to such a law, but 
show that in the lipolysis tested toxicity does not vary inversely with 
_the solution tension. On the other hand, a reaction, in the case of 
electrolytes at least, in which solution tension is not a factor, is 
hardly imaginable, but the same is true of temperature, etc. 
CONCLUSION. 
The toxicity of the salts tested does not under the conditions 
herein specified, vary inversely with the decomposition tension of 
those salts. 
* Berc, W. N., and Gies, W. J.: Journal of biological chemistry 1907; ii. 
PP. 489-546. 
